2023 Doom source code leak

In September 2023, a Compact Disc containing the source code to various versions of Doom, including Mac and DOS versions of Doom 2 and Ultimate Doom was auctioned on eBay by an anonymous seller. The auction was won by an internet user who dumped the disc and anonymously uploaded it to archive.org. The disc contains versions of the Doom source code dated February 15th, 1996 earlier than the one officially released by id Software in 1997, as well as many development assets that were not released by Romero in the 2015 Doom source data release.

The original purpose of the disc is unclear but it seems to have been mainly intended for the distributor of the Macintosh version of Ultimate Doom, as the CD is labelled "Mac Doom/Doom II/Ultimate Doom Source", is formatted for Mac OS, and contains many Mac OS utilities. Despite its date, it does not seem to contain anything related to Final Doom, which was released only a few months later.